The ability of battery powered warning lights to operate for long periods of time has heretofore been somewhat diminished by the fact that such warning lights have used conventional incandescent lights or flash tubes having electrical power requirement that, under continuous operating conditions, may drain the battery within a matter of hours which is expensive and time consuming and particularly so when a large number of such warning lights are employed to designate driving lanes along a length of road under repair.
In view of the foregoing, there has long been a need to extend the operating life of battery powered warning lights without sacrificing the level of illumination provided thereby.
The present invention addresses the problem of extending operating life of battery powered warning lights by combining a low power draw electroluminescent light panel as the light source that in turn is enclosed by a lens containing fluorescent material that fluoresces to enhance the brightness of the electroluminescent panel light incident thereupon.
Electroluminescent lighting panels have been known for many years. Such panels are made by laminating films together and can be in the order of 20 mils or less in thickness and can range from being somewhat rigid to flexible depending upon the materials selected. The panels generally comprise a phosphorescent layer and a dielectric layer sandwiched between a transparent electrode layer (commonly made with indium oxide) and a more conventional electrode layer such as made from metalized plastic and all of which is commonly enclosed by a transparent film providing a moisture barrier about the panel. Electrodes are fixed to the electrode layers (commonly by a suitable adhesive) and a lower power alternating electrical fluid imposed between the electrodes causes the excited phosphor particles to glow to provide low power draw lighting that heretofore has been limited in use to instrument panel lighting in vehicles and the like.
Greater detail in the design of electroluminescent panels can be found for example in U.S. Pat. Nos. 4,767,966; 4,904,901 and 5,036,249, the disclosures of which are incorporated herein by reference.
The use of fluorescent materials in reflective marker and other signs and in lighting members utilizing conventional incandescent light bulbs or zenon type gas-filled tubing is also known and is described for example in U.S. Pat. Nos. 3,766,881; 4,677,010; 4,011,665 and 4,215,390, the disclosures of which are incorporated herein by reference.
No one heretofore had thought to combine the low power draw glow provided by electroluminescent panel lighting with a lens containing a fluorescent material operative to fluoresce and enhance the brightness of the light sufficiently to enable effective operation as a warning light over long periods of time.